It is common practice in the microelectronic art for connections to hybrid circuits which are housed in sealed metal boxes to be made via feed-throughs in the form of little metal pins which pass through the thickness of the box wall with each pin being sealed to the wall and insulated therefrom by a bead of glass. The pins project inside the box for connection to the hybrid circuits housed therein, and outside the box for connection to circuits external thereto. Generally speaking, for connection to an external circuit, the pins either project a short way outside the box, in which case they are intended for connection to a complementary connector, or else they project a relatively long way, in which case they are intended for individual connection to conductor leads. The leads are usually wound round the corresponding pins and then soldered thereto.
Feed-throughs that project only a short way outside the box have the advantage being more compact than long feed-throughs, but they cannot be used for direct soldered connections. Feed-throughs which project a long way outside the box naturally increase the overall outside dimensions of the box, and even though they are specifically intended for direct soldered connections, in practice great care must be taken to avoid accidental short circuits between pins or between a pin and the box. Short circuits can arise either by excess solder, or by the pins being bent.
In a first aspect, preferred embodiments of the present invention provide feed-throughs for metal boxes housing hybrid circuits which feed-throughs are equally suitable for connection to external circuits by direct soldering or by a releasable connector, depending on user requirements.